Overclocking at all is a bad idea unless you have aftermarket cooling. Especially considering how much heat a Pentium 4 produces even at stock speeds. And to be honest you could overclock to 5 or 6 Ghz and you would still have a single core Pentium 4. Meaning the only way to improve that chip is a full system upgrade. Overclocking will not help.
And most importantly since you don't know what motherboard you have you probably have a prebuilt computer from Dell or HP or something? Those OEM companies lock their BIOS to prevent overclocking. They want you to buy a new computer not improve the one you have.